(fxlognot 0)
=> -1
(fxlognot -1)
=> 0
(fxlognot 1)
=> -2
(fxlognot -2)
=> 1
(fxlognot 536870911)
=> -536870912
(fxlognot -536870912)
=> 536870911
(fxlognot (fxlognot 237463))
=> 237463